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排序方式: 共有211条查询结果,搜索用时 15 毫秒
1.
Tetiana Gren Bohdan Ostash Yaroslav Hrubskyy Stepan Tistechok Victor Fedorenko 《Folia microbiologica》2014,59(2):147-153
Bacteria-assisted bioremediation is widely recognized as a low-cost method to minimize the consequences of soil pollution with toxic metals originating from industrial sites. Strains used in bioremediation have to deal with high metal load via biosorption, reduction, bioprecipitation, metal sequestration, and/or chelation. Actinobacteria, and streptomycetes in particular, are considered a perspective group for bioremediation as natural soil inhabitants with extensive secondary metabolism. Nevertheless, there is no reference information on survival of the model streptomycetes in the presence of the most abundant metal pollutants. Also, there are no reports describing the selection approaches towards improvement of bioremediation properties. In this work, the resistance of Streptomyces coelicolor M145 and Streptomyces sioyaensis Lv81 to certain transition metals and their growth under different pH values are described for the first time. Spontaneous chromate-resistant S. sioyaensis Lv81-138 strain was selected in the course of this work. Strain Lv81-138 is the most efficient actinobacterial Cr(VI) reducer reported so far, capable of converting 12 mmol/L of Cr(VI) into Cr(III) in a medium supplemented with 50 mmol/L K2CrO4. 相似文献
2.
Eighty-four species of Chironomidae were collected, using emergence traps, from three poor fens located in the Experimental Lakes Area (ELA) of northwestern Ontario. Of these, 37 were considered to be true peatland fauna. The majority (23) of the peatland species are new North American or Canadian records and, of these, 10 are previously undescribed. Numbers m−2 yr−1 emerging from the fens were similar to neighbouring lakes but biomass (mg) m−2 yr−1 emerging was much less, indicating the small average size of the fen chironomids. Emergence began in early May and was virtually completed by late July-early August in all three years of the study. Most of the emergence occurred early in the season. Eight species accounted for ≥90% of the emergence. Five of these, Gymnometriocnemus (R.) acigus Saeth., Doithrix villosa Saeth. and Subl., Pseudorthocladius (s.s.) destitutus Saeth. and Subl., P. (s.s.) curtistylus (Goetgh.), and Paramerina nr. smithae (Subl.) had univoltine life cycles and relatively stichronous emergences. Pseudosmittia forcipata (Goetgh.) was bivoltine, and Limnophyes minimus (Meig.) and Smittia nr. nudipennis Geotgh. had protracted emergence periods that made voltinism difficult to determine. Characteristic features of the chironomid fauna of peatlands at ELA are discussed. The general applicability of these features to peatlands, and needs for further research in these neglected but extensive Canadian habitats are considered. 相似文献
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Early after-depolarisations induced by noradrenaline may be initiated by calcium released from sarcoplasmic reticulum 总被引:1,自引:0,他引:1
We investigated the effect of 10–8 M noradrenaline (NA) on [Ca2+], and electrical activity of single myocytes of guinea-pig ventricular myocardium loaded with Indo 1-AM. Membrane potential was recorded by means of the patch electrode and patch amplifier set to the current clamp mode. Cells were stimulated at a rate of 30/min by 3 ms pulses of the current injected through the recording electrode. Superfusion of NA resulted in slight shortening of action potentials (APs), increase in rate of rise and amplitude of the respective Ca2+ transients, and appearance of secondary Ca2+ transients of two kinds: 1. appearing before repolarisation of AP and decay of the preceding Ca2+ transient were completed and 2. appearing between the APs. We named them early after-transients (EAT) and delayed after-transients (DAT), respectively. Without any additional intervention EATS caused some prolongation of APs duration and DATs resulted in subthreshold delayed after-depolarisations (DADS). When sarcolemmal K+ conductance was decreased by tetraethylammonium (TEA) in the patch electrode or 20 M BaCl2 in the Tyrode solution, EATs initiated early after depolarizations (EADs) and DATs initiated suprathreshold DADs triggering full-sized APs. Superfusion of 30.0 mM Na+ (replaced with LiCl) resulted in reduction of AP duration by -70% and appearance of DATs. Also, the frequent multiple oscillations of Ca 2+ concentration were often observed. Neither DATs nor the oscillations had any affect on electrical activity of the cells. Their electrogenicity could not be increased by TEA or 20.0 M Ba2+. EATs and DATs and their respective EADs and DADs could not be initiated by NA or low Na+ superfusion in the cells pretreated with 2 × 10–7 M thapsigargin, a selective blocker of Ca2+-ATPase of sarcoplasmic reticulum (SR). We conclude that in contrast to the current hypothesis, EADs can be initiated by Ca2+ released early in the cardiac cycle from the overloaded SR, and that electrogenicity of both types of Ca2+ oscillations critically depends on the sarcolemmal K+ conductance. 相似文献
5.
We have examined the effect of ethacrynic acid on mitochondrial morphology and distribution as well as on cellular toxicity in cultured human fibroblasts, African Green Monkey B-SC-1 kidney cells, and Chinese hamster ovary cells. Treatment of the above cells with 66 μM ethacrynic acid causes no reduction in cell viability after 2 h but is cytotoxic upon prolonged (6–7 days) exposure. Ethacrynic acid treatment for up to 2 h is found to cause novel shape changes and redistribution of mitochondria, as assessed by immunofluorescence and electron microscopy. Early effects include the transient formation of a mitochondrial reticulum involving the majority of mitochondria, and these reticula are aligned along microtubules. At later times within 2 h, mitochondrial distributions become disoriented (show no association with microtubules), and an aggregation and final positioning of mitochondria around the nucleus is observed. Whole mount electron microscopy shows that mitochondria in treated cells increase in length and form junctions, indicating reticula result from mitochondrial fusion. Electron microscopy of sections through ethacrynic acid induced reticula demonstrates structural continuity in mitochondria at branch points and the presence of regular cristae. Staining of endoplasmic reticulum and mitochondria in intact cells with the cyanine dye 3,3′-dihexyloxacarbocyanine iodide provides evidence of concurrent aggregation of endoplasmic reticulum. Rhodamine 123 staining of living cells followed by immunofluorescent labeling of mitochondria in the same cells indicates that all mitochondria retain a transmembrane potential during the druginduced shape changes and redistributions. The described effects of ethacrynic acid on mitochondrial morphology as well as on cellular toxicity are completely prevented by 0.5 mM dithiothreitol, indicating that ethacrynic acid is acting as a sulfhydryl reagent to produce the observed effects. The above observations also indicate that ethacrynic acid effects on mitochondrial morphology are an early event in the drug-induced cytotoxicity. The generation of varied mitochondrial morphologies by fusion and fission of mitochondria and its modulation by agents such as ethacrynic acid are discussed. © 1994 wiley-Liss, Inc. 相似文献
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Artur Burdzy Bohdan Skalski Ewa Bia? Andrzej Kowalewski Stefan Paszyc Rysard W. Adamiak 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):979-982
Abstract New route to oligodeoxynucleotides labeled with fluorescent luminarine was explored. Regioselective oxidation of 6-methylthio-purines to 6-methylsulphoxides reactive toward pyridine was achieved. Upon UV irradiation of 6-pyridinium-purines oligonucleotide cleavage instead of phototransformation to luminarine was observed. 相似文献
8.
Helena Rudnicka Tadeusz Debniak Cezary Cybulski Tomasz Huzarski Jacek Gronwald Jan Lubinski Bohdan Gorski 《Molecular biology reports》2013,40(12):6619-6623
BRCA1 and BRCA2 are two major genes associated with familial breast and ovarian cancer susceptibility. In Poland standard BRCA gene test is usually limited to Polish founder BRCA1 mutations: 5382insC, C61G and 4153delA. To date, just a few single large genomic rearrangements (LGRs) of BRCA1 gene have been reported in Poland. Here we report the first comprehensive analysis of large mutations in BRCA1 and BRCA2 genes in this country. We screened LGRs in BRCA1 and BRCA2 genes by multiplex ligation-dependent probe amplification in 200 unrelated patients with strong family history of breast/ovarian cancers and negative for BRCA1 Polish founder mutations. We identified three different LGRs in BRCA1 gene: exons 13-19 deletion, exon 17 deletion and exon 22 deletion. No LGR was detected in BRCA2 genes. Overall, large rearrangements accounted for 3.7 % of all BRCA1 mutation positive families in our population and 1.5 % in high-risk families negative for Polish founder mutation. 相似文献
9.
Krzysztof Mędrek Piotr Magnowski Bartłomiej Masojć Anita Chudecka-Głaz Bogdan Torbe Janusz Menkiszak Marek Spaczyński Jacek Gronwald Jan Lubiński Bohdan Górski 《Molecular biology reports》2013,40(3):2145-2147
Among many alterations within the TP53 gene the rs1042522 (C72G, p.Pro72Arg) has been associated with numerous cancers , however the results differ between populations for opposite Pro or Arg alleles. Similar thus inconclusive results are observed in ovarian cancer, which may suggest that the rs1042522 does not influence ovarian carcinogensis directly, but might be linked to another pathogenic alteration. WRAP53 which overlaps the TP53 is required to maintain normal levels of p53 upon DNA damage, but also when altered may independently increase the risk of cancer. To evaluate the association between three SNPs located in WRAP53–TP53 region: rs1042522, rs2287497, rs2287498 and ovarian cancer risk in Polish population we genotyped 626 cases and 1,045 healthy controls. Our results provide the evidence for an association between studied SNPs and a risk of invasive ovarian cancer in Poland. We found that CC homozygotes in rs1042522 were more frequent in cancers when compared to controls (OR = 1.46, p = 0.03). Similarly in WRAP53 both TT homozygotes in rs2287497 (OR = 1.95, p = 0.03) and AA homozygotes in rs2287498 (OR = 2.65, p = 0,01) were more frequent among cases than healthy individuals. There is also a suggestive evidence that specific homozygosity of studied SNPs in TP53–WRAP53 region is significantly overrepresented in ovarian cancer patients. In conclusion SNPs in WRAP53 (rs2287497 and rs2287498) have stronger association with an ovarian cancer risk than rs1042522 in TP53. 相似文献
10.
Bohdan Bilyk Stephen Weber Maksym Myronovskyi Oksana Bilyk Lutz Petzke Andriy Luzhetskyy 《Applied microbiology and biotechnology》2013,97(1):351-359
We report here the in vivo expression of the synthetic transposase gene himar1(a) in Streptomyces coelicolor M145 and Streptomyces albus. Using the synthetic himar1(a) gene adapted for Streptomyces codon usage, we showed random insertion of the transposon into the streptomycetes genome. The insertion frequency for the Himar1-derived minitransposons is nearly 100 % of transformed Streptomyces cells, and insertions are stably inherited in the absence of an antibiotic selection. The minitransposons contain different antibiotic resistance selection markers (apramycin, hygromycin, and spectinomycin), site-specific recombinase target sites (rox and/or loxP), I-SceI meganuclease target sites, and an R6Kγ origin of replication for transposon rescue. We identified transposon insertion loci by random sequencing of more than 100 rescue plasmids. The majority of insertions were mapped to putative open-reading frames on the S. coelicolor M145 and S. albus chromosomes. These insertions included several new regulatory genes affecting S. coelicolor M145 growth and actinorhodin biosynthesis. 相似文献